This invention relates generally to improvements to ball valves. More particularly, but not by way of limitation, this invention relates to an improved valve seat.
A ball valve consists of a valve body having a ball receiving cavity with aligned inlet and outlet passages leading to and from the cavity. A ball with an opening formed therethrough is rotatably supported in the cavity between the inlet and outlet passages. Means is provided for rotating the ball to an open position wherein its opening is aligned with the inlet and outlet passages in an open position and to a closed position where the opening is out of alignment with the inlet and outlet passages. Sealing between the ball and the body is accomplished by two ring-shaped seats located in the valve body on opposite sides of the cavity for engagement with the ball and which define a portion of the inlet and outlet passages respectively. These seats each have sealing surfaces for engagement with the ball on one side and the valve body on the other. A wide variety of seat materials and designs have been proposed in the prior art, many of which use elastomeric materials which are incapable of utilization in handling fluids in abrasive, chemical, or high-temperature environments. For instance, in a high-temperature situation, i.e. temperatures above 800.degree. F., elastomeric materials are destroyed. In addition, because of the high-temperature environment of the fluids, sufficient allowance for the expansion of the valve body, the ball valve and its seats are not adequately provided for.